The ESP32-C5, Finally Espressif Goes Dual-Band

January 26, 2025 by Jenny List 5 Comments

The ESP32 series of microcontrollers have been with us for quite a few years now, providing a powerful processor and wireless connectivity for not a huge outlay. We’ve seen a bunch of versions over the years with both Tensilica and RISC-V cores, but so far the ones with radios have all only serviced 2.4 GHz WiFi. That’s about to change to include 5GHz with the new C5 variant though, and [Andreas Speiss] has been lucky enough to get his hands on a prototype dev kit

It’s very similar to the C6, which we’re already used to beyond the dual-band 2.4GHz and 5GHz radio from a software point of view. The C5 is so new that the company has yet to incorporate the new chip into the Arduino IDE. He shows it working and detecting both networks though, and speculates a little about its eventual marketing.

Interesting to us is the dual-band antenna, with branches for both frequencies on the same PCB. We’d be interested to see the real-world performance of this, and also whether they produce a version with separate outputs for each band. The full video is below the break. In the meantime, watch out for this chip appearing on the market.

It’s not the only Espresif chip we’re anticipating at the moment.

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Putting Cheap Motorcycle Tachometers To Work

January 18, 2025 by Tom Nardi 15 Comments

With so much data being thrown at our eyeballs these days, it’s worryingly easy for the actually important stuff to slip by occasionally. So when [Liam Jackson] wanted a way to visualize the number of test failures popping up in the continuous integration system at work, he went with a novel but effective solution — universal motorcycle tachometers.

It turns out these little gauges can be had for under $10 a piece from the usual overseas retailers, and are very easy to drive with a microcontroller. As [Liam] explains, all you need to do other than providing them with 12 volts, is feed them a PWM signal. Even though the gauges are designed for a 12 V system, they apparently don’t have any problem responding to the 5 V logic level from the Arduino’s pins.

As for the frequency he says that 1,000 RPM corresponds to 16.66 Hz, so you can just multiply up from there to show whatever number you wish. That said, [Liam] warns that the gauges draw several hundred milliamps once the needle gets into the two digit range, so keep that in mind. Conveniently, those number happen to be in red anyway…

For his particular application, [Liam] put three of the gauges together to create a very handsome dashboard. If you want to recreate his setup exactly he’s made the STLs available for the gauge cluster housing. Note the small OLED at the center, this offers a way to show a bit more context than the three analog gauges alone can express, especially if you’ve got an application where you might be switching between multiple data sources.

Over the years we’ve seen several projects that repurposed analog gauges of various types, often for showing computer performance, but they generally involved having to drive the galvanometers directly. That these tachometers can simply be fed a simple digital signal should make implementing them into your project much easier.

Piezo Buzzer Makes A Drum

January 15, 2025 by Jenny List 6 Comments

The humble piezo disc buzzer is much more than something that makes tinny beeps in retro electronic equipment, it can also be used as a sensor. Tapping a piezo buzzer gives an interesting waveform, with a voltage spike followed by an envelope, and then a negative rebound voltage. It’s something [Igor Brichkov] is using, to make a simple but effective electronic drum.

First of all, the output of the buzzer must be tamed, which he does by giving it a little impedance to dissipate any voltage spikes. There follows some simple signal conditioning with passive components, to arrive at an envelope for the final drum sound. How to turn a voltage into a sound? Using a voltage controlled amplifier working on a noise source. The result is recognizably the drum sound, entirely in electronics.

In a world of digital music it’s easy to forget the simpler end of sound synthesis, using circuits rather than software. If you hanker for the Good Old Days, we have an entire series on logic noise, doing the job with 4000 series CMOS logic.

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Rethinking Your Jellybean Op Amps

January 6, 2025 by Dan Maloney 43 Comments

Are your jellybeans getting stale? [lcamtuf] thinks so, and his guide to choosing op-amps makes a good case for rethinking what parts you should keep in stock.

For readers of a certain vintage, the term “operational amplifier” is almost synonymous with the LM741 or LM324, and with good reason. This is despite the limitations these chips have, including the need for bipolar power supplies at relatively high voltages and the need to limit the input voltage range lest clipping and distortion occur. These chips have appeared in countless designs over the nearly 60 years that they’ve been available, and the Internet is littered with examples of circuits using them.

For [lcamtuf], the abundance of designs for these dated chips is exactly the problem, as it leads to a “copy-paste” design culture despite the far more capable and modern op-amps that are readily available. His list of preferred jellybeans includes the OPA2323, favored thanks to its lower single-supply voltage range, rail-to-rail input and output, and decent output current. The article also discussed the pros and cons of FET input, frequency response and slew rate, and the relative unimportance of internal noise, pointing out that most modern op-amps will probably be the least thermally noisy part in your circuit.

None of this is to take away from how important the 741 and other early op-amps were, of course. They are venerable chips that still have their place, and we expect they’ll be showing up in designs for many decades to come. This is just food for thought, and [lcamtuf] makes a good case for rethinking your analog designs while cluing us in on what really matters when choosing an op-amp.

One Small Step: All About Stepper Motors

January 6, 2025 by Maya Posch 12 Comments

The primary feature of stepper motors is listed right within their name: their ability to ‘step’ forwards and backwards, something which they (ideally) can do perfectly in sync with the input provided to their distinct coils. It’s a feature that allows the connected controller to know the exact position of the stepper motor, without the need for any sensor to provide feedback after a movement, saving a lot of hardware and effort in the process.

Naturally, this is the optimal case, and there are a wide number of different stepper motor configurations in terms of coil count, types of rotors and internal wiring of the coils, as well as complications such as skipped steps due to mechanical or driver issues. Despite this, in general stepper motors are quite reliable, and extremely versatile. As a result they can be found just about anywhere where accurate, step-based movement is desirable, such as (3D) printers and robotics.

For each application the right type of stepper motor and driving circuit has to be determined, of course, as they also have many reasons why you’d not want to use them, or just a particular type. When diving into a new stepper motor-based project, exactly what are the considerations to pay attention to?

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DIYFPV: A New Home For Drone Builders

January 2, 2025 by Tom Nardi 30 Comments

If you’re looking to get into flying first-person view (FPV) remote controlled aircraft, there’s an incredible amount of information available online. Seriously, it’s ridiculous. In fact, between the different forums and the countless YouTube videos out there, it can be difficult to sort through the noise and actually find the information you need.

What if there was one location where FPV folks could look up hardware, compare notes, and maybe even meet up for the occasional flight? That’s the idea behind the recently launched DIYFPV. In its current state the website is a cross between a social media platform, a hardware database, and a tech support forum.

Being able to look up parts to see who has them in stock and for what price is certainly handy, and is likely to become a very valuable resource, especially as users start filling the database with first-hand reviews. There’s no shortage of social media platforms where you can post and chat about FPV, but pairing that with a dedicated tech support section has promise. Especially if the solutions it produces start getting scrapped by show up in search engines.

But the part of DIYFPV that has us the most interested is the interactive builder tool. As explained in the announcement video below, once this feature goes live, it will allow users to pick parts from the database and virtually wire them together. Parts are represented by high-quality illustrations that accurately represent connectors and solder pads, so you won’t be left guessing where you’re supposed to connect what. Schematics can be shared with others to help with troubleshooting or if you want to get feedback.

The potential here is immense. Imagine a function to estimate the mass of the currently selected electronics, or a simulation of how much current it will draw during flight. It’s not clear how far DIYFPV plans on taking this feature, but we’re eager to find out.

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Playing Around With The MH-CD42 Charger Board

December 27, 2024 by Tom Nardi 11 Comments

If you’ve ever worked with adding lithium-ion batteries to one of your projects, you’ve likely spent some quality time with a TP4056. Whether you implemented the circuit yourself, or took the easy way out and picked up one of the dirt cheap modules available online, the battery management IC is simple to work with and gets the job done.

But there’s always room for improvement. In a recent video, [Det] and [Rich] from Learn Electronics Repair go over using a more modern battery management board that’s sold online as the MH-CD42. This board, which is generally based on a clone of the IP5306, seems intended for USB battery banks — but as it so happens, plenty of projects that makers and hardware hackers work on have very similar requirements.

So not only will the MH-CD42 charge your lithium-ion cells when given a nominal USB input voltage (4.5 – 5 VDC), it will also provide essential protections for the battery. That means looking out for short circuits, over-charge, and over-discharge conditions. It can charge at up to 2 A (up from 1 A on the TP4056), and includes a handy LED “battery gauge” on the board. But perhaps best of all for our purposes, it includes the necessary circuitry to boost the output from the battery up to 5 V.

If there’s a downside to this board, it’s that it has an automatic cut-off for when it thinks you’ve finished using it; a feature inherited from its USB battery bank origins. In practice, that means this board might not be the right choice for projects that aren’t drawing more than a hundred milliamps or so.

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